Clinical Hemorheology and Microcirculation - Volume 62, issue 2
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Clinical Hemorheology and Microcirculation, a peer-reviewed international scientific journal, serves as an aid to understanding the flow properties of blood and the relationship to normal and abnormal physiology. The rapidly expanding science of hemorheology concerns blood, its components and the blood vessels with which blood interacts. It includes perihemorheology, i.e., the rheology of fluid and structures in the perivascular and interstitial spaces as well as the lymphatic system. The clinical aspects include pathogenesis, symptomatology and diagnostic methods, and the fields of prophylaxis and therapy in all branches of medicine and surgery, pharmacology and drug research.
The endeavour of the Editors-in-Chief and publishers of
Clinical Hemorheology and Microcirculation is to bring together contributions from those working in various fields related to blood flow all over the world. The editors of
Clinical Hemorheology and Microcirculation are from those countries in Europe, Asia, Australia and America where appreciable work in clinical hemorheology and microcirculation is being carried out. Each editor takes responsibility to decide on the acceptance of a manuscript. He is required to have the manuscript appraised by two referees and may be one of them himself. The executive editorial office, to which the manuscripts have been submitted, is responsible for rapid handling of the reviewing process.
Clinical Hemorheology and Microcirculation accepts original papers, brief communications, mini-reports and letters to the Editors-in-Chief. Review articles, providing general views and new insights into related subjects, are regularly invited by the Editors-in-Chief. Proceedings of international and national conferences on clinical hemorheology (in original form or as abstracts) complete the range of editorial features.
The following professionals and institutions will benefit most from subscribing to
Clinical Hemorheology and Microcirculation: medical practitioners in all fields including hematology, cardiology, geriatrics, angiology, surgery, obstetrics and gynecology, ophthalmology, otology, and neurology. Pharmacologists, clinical laboratories, blood transfusion centres, manufacturing firms producing diagnostic instruments, and the pharmaceutical industry will also benefit.
Important new topics will increasingly claim more pages of
Clinical Hemorheology and Microcirculation: the role of hemorheological and microcirculatory disturbances for epidemiology and prognosis, in particular regarding cardiovascular disorders, as well as its significance in the field of geriatrics. Authors and readers are invited to contact the editors for specific information or to make suggestions.
Abstract: Silica nanomaterials (NMs) are widely used in semiconductor, agriculture, cosmetics, and biomedical applications, in addition to other industries. We investigated the toxic effect of silica NMs on rheological characteristics of human red blood cells (RBCs), including hemolysis, deformability, aggregation, and morphological changes. Red blood cells were exposed to silica nanoparticles (d =∼200 nm) or silica nanowires (d =∼200 nm, l = 1μ m or 10μ m) at a range of concentrations and incubation times. Rheological characteristics were measured using microfluidic-laser diffractometry and aggregometry. Overall, at a concentration greater than 12.5μ g/ml, the hemolytic activity was shown to be in the order of nanoparticles,…short nanowires, and long nanowires. Elongation index (EI) values were insignificant in the RBCs exposed to each of the silica NMs at a concentration of 12.5μ g/ml. Aggregation index (AI) values decreased in the short silica nanowires at a concentration of 12.5μ g/ml compared to other silica NMs. Therefore, the safe concentration of silica NMs for toxicity, in this study, was considered less than 12.5μ g/ml. These hemorheological results provided insight into the interaction between RBCs and silica NMs; they will also help assess the risk of NMs’ toxicity in the blood.
Abstract: In this article, a periodic developing blood flow in a capillary is simulated using a non-linear viscoelastic model for the first time. Here, the Giesekus model is used as the constitutive equation, and based on the experimental data, the best value for the mobility factor and zero shear rate viscosity are derived. The numerical solution of the problem is obtained using the finite volume method. The algorithm of the solution is pressure implicit with splitting of operators (PISO). The simulation carried out using the Giesekus, Oldroyd-B and Newtonian models and the results indicate that the Giesekus model presents a more…accurate solution for the stress and velocity fields than the Newtonian and Oldroyd-B models. The previous studies on this problem were restricted to the linear and quasi-linear viscoelastic models. It is shown that only non-linear viscoelastic models can accurately describe the experimental data of unsteady blood flow in capillaries.
Abstract: Excessive time for analysis may impede microcirculatory studies with large amounts of video data. Engaging more personnel in the analyses seems to be a rational approach in that scenario and could shorten the time-interval between capturing images and obtaining results. Our hypothesis was that novice users would be able to determine standard microcirculatory parameters using a semi-automated software with an acceptable degree of variability after participating in a standardized interactive training session. 14 volunteers were included in the study. All volunteers analyzed separately the same sample video after the training. The kappa statistic was calculated for the primary outcome parameter…microvascular flow index (MFI) within small and large vessels and indicated a fair level of agreement in the results of the novice users. A standardized interactive tutorial can be useful to teach microcirculatory analysis in previously untrained subjects.
Abstract: BACKGROUND: Although numerous risk factors for arteriovenous fistulae (AVF) dysfunction have been identified, these risk factors do not explain all cases of AVF dysfunction. Because of the importance of blood pressure variability (BPV) in vascular injury, the predictive value of BPV for AVF dysfunction, was evaluated in this prospective cohort study. METHODS: Twenty-four-hour BP monitoring at the intervals of dialysis was recorded every 3 months in 137 patients. The expression of smooth muscle actin (SMA) and the infiltration of mononuclear cells and T lymphocytes were determined by immunohistochemistry on the specimens of fistula vessels. RESULTS: Eighteen…patients developed AVF dysfunction. Cox proportional hazards multivariate analysis revealed a significant relationship between fistula dysfunction and daytime systolic-BPV (d-SBPV), nighttime systolic-BPV (n-SBPV), diabetes mellitus, and initial venous diameter. Patients with AVF dysfunction were observed to have increased SMA expression and more infiltration of inflammatory cells in venous walls compared with the controls. A significant correlation between SBPV and the infiltration of CD68-positive cells was observed. CONCLUSIONS: Our study showed that the degrees of SBPV were significantly associated with the risk of AVF dysfunction. Potentially, the increase of SBPV will aggravate venous wall inflammation and may play a role in AVF dysfunction.
Abstract: To investigate the relationship between blood rheology and endothelial function in patients with coronary risk factors, brachial arterial flow-mediated vasodilatation (FMD), an index of endothelial function and blood passage time (BPT), an index of blood rheology, and fasting blood cell count, glucose metabolism, and plasma fibrinogen, lipid, C-reactive protein, and whole blood viscosity levels were measured in 95 patients with coronary risk factors and 37 healthy controls. Brachial arterial FMD after reactive hyperemia was assessed by ultrasonography. BPT was assessed using the microchannel method. In healthy controls, BPT significantly correlated with FMD (r = – 0.325, p < 0.05), HDL cholesterol…(r = – 0.393, p < 0.05), body mass index (BMI; r = 0.530, p < 0.01), and plasma fibrinogen concentration (r = 0.335, p < 0.05). In a multivariate regression analysis adjusted for all clinical variables, BPT remained significantly associated with BMI and fibrinogen, but not with FMD, in healthy controls. In patients with coronary risk factors, BPT significantly correlated with FMD (r = – 0.331, p < 0.01), HDL cholesterol (r = – 0.241, p < 0.05), BMI (r = 0.290, p < 0.01), hematocrit (r = 0.422, p < 0.001), white blood cell count (r = 0.295, p < 0.01), platelet count (r = 0.204, p < 0.05), and insulin (r = 0.210, p < 0.05). In a multivariate regression analysis adjusted for all clinical variables, BPT remained strongly associated with FMD and hematocrit in patients with coronary risk factors. These data indicate that BPT is closely associated with FMD in patients with coronary risk factors and suggest that the measurement of blood rheology using the microchannel method may be useful in evaluating brachial arterial endothelial function as a marker of atherosclerosis in these patients.
Abstract: Platelets play a major role in maintaining endothelial integrity and hemostasis. Of the various soluble agonists, ADP is an important in vivo stimulus for inducing platelet aggregation. In this study, a simple, rapid, and affordable method was designed for testing bleeding time (BT) and platelet aggregation with a two-channel microfluidic chip. Whole blood migration ratio (MR) from a microchip system was evaluated in comparison to the closure time (CT) from PFA-100 assays (Siemens, Germany) and CD62P expression on platelets. To induce platelet aggregation, a combination of collagen (1.84 mg/ml) and ADP (37.5 mg/ml) were used as agonists. After adding the agonists…to samples, whole blood MR from the microchip system was measured. The outcome of the assessment depended on reaction time and agonist concentration. MR of whole blood from the microchip system was significantly correlated with CT from PFA-100 (r = 0.61, p < 0.05, n = 60). In addition, MR was negatively correlated with CD62P expression (r =−0.95, p < 0.05, n = 60). These results suggest that the measurement of MR using agonists is an easy, simple and efficient method for monitoring platelet aggregation in normal and ADP-receptors defective samples, along with the BT test. Thus, usage of the current microfluidic method could expand to diverse applications, including efficacy assessments in platelet therapy.
Abstract: Shear stress is known to induce platelet activation and aggregation. The red blood cell (RBC) aggregation test requires the application of shear stress for the cells to disaggregate for initialization. We tested the hypothesis that applying shear stress may activate platelets, which can influence RBC aggregation. The present study used a commercial microchip-based aggregometer (RheoSCan-AnD300) with a rotating stirrer for RBC disaggregation. Whole blood samples were exposed to different magnitudes of shear stress with various shearing times. As the rotational speed was increased up to 2800 rpm, the RBC aggregation index (AI) of the whole blood increased by up to 30%…(p < 0.05), whereas that of the platelet-excluded blood samples did not show any apparent alteration. The AI also increased in proportion with the stirring time. The data suggest that high shear stress affects RBC aggregation through shear-induced platelet aggregation.
Abstract: Red blood cell (RBC) deformability is severely decreased in patients with sickle cell anemia (SCA), which plays a role in the pathophysiology of the disease. However, investigation of RBC deformability from SCA patients demands careful methodological considerations. We assessed RBC deformability by ektacytometry (LORRCA MaxSis, Mechatronics, The Netherlands) in 6 healthy individuals and 49 SCA patients and tested the effects of different heights of the RBC diffraction patterns, obtained by altering the camera gain of the LORRCA, on the result of RBC deformability measurements, expressed as Elongation Index (EI). Results indicate that the pattern of RBCs from control subjects adopts…an elliptical shape under shear stress, whereas the pattern of RBCs from individuals with SCA adopts a diamond shape arising from the superposition of elliptical and circular patterns. The latter represent rigid RBCs. While the EI measures did not change with the variations of the RBC diffraction pattern heights in the control subjects, we observed a decrease of EI when the RBC diffraction pattern height is increased in the SCA group. The differences in SCA EI values measured at 5 Pa between the different diffraction pattern heights correlated with the percent of hemoglobin S and the percent of sickled RBC observed by microscopy. Our study confirms that the camera gain or aperture of the ektacytometer should be used to standardize the size of the RBC diffraction pattern height when measuring RBC deformability in sickle cell patients and underscores the potential clinical utility of this technique.
Abstract: Angiogenesis is essential for wound healing, and angiogenesis impairment can result in chronic ulcers. Studies have shown that the sympathetic nervous system has an important role in angiogenesis. In recent years, researchers have focused on the roles of sympathetic nerves in tumor angiogenesis. In fact, sympathetic nerves can affect angiogenesis in the wound healing of soft tissues, and may have a similar mechanism of action as that seen in tumorigenesis. Sympathetic nerves act primarily through interactions between the neurotransmitters released from nerve endings and receptors present in target organs. Among this, activation or inhibition of adrenergic receptors (mainly β-adrenergic receptors)…influence formation of new blood vessels considerably. As sympathetic nerves locate near pericytes in microvessel, go along the capillaries and there are adrenergic receptors present in endothelial cells and pericytes, sympathetic nerves may participate in angiogenesis by influencing the endothelial cells and pericytes of new capillaries. Studying the roles of sympathetic nerves on the angiogenesis of wound healing can contribute to understanding the mechanisms of tissue repair, tissue regeneration, and tumorigenesis, thereby providing new therapeutic perspectives.